PROJECT SUMMARY The goal of our research is to identify ocular biomarkers that have diagnostic and potentially prognostic utility in Alzheimer's Disease (AD), and establish a relationship to cognition. We seek to determine this relationship in an already established cohort of patients (the Vitreous Biomarkers Study, or VBS) with eye disease where protein biomarkers have been identified in the vitreous humor of the eye and found to be correlated to cognitive function scores on mini-mental status examination (MMSE). There is a need for sensitive and specific diagnostic tests that can detect AD in the early stages. We hypothesize that ocular levels of A? and Tau in the aqueous humor of the eye as well as retinal biomarkers of neurodegeneration imaged by Optical Coherence Tomography (OCT), combined with cognitive assessments, may offer a predictive value for detection of early AD. In the VBS, we found that levels of beta amyloid (A?40, A?42), and total Tau (tTau) in the vitreous humor are correlated with cognitive function scores obtained by mini-mental status examination (MMSE). Drawing from the same patient cohort, we seek to establish the presence of the same proteins in the aqueous humor of the eye (which is more clinically accessible than the vitreous humor), obtain OCT images to look for retinal biomarkers, and repeat MMSE testing to look longitudinally at cognition, and correlate all eye biomarkers with cognition. Additionally, we seek to validate the protein levels in the aqueous and vitreous humor of eyes from postmortem subjects. If a relationship of protein and retinal biomarkers to cognition can be shown, our knowledge of the eye's role in AD will be increased substantially and it will establish the eye as potentially playing a central role in how we diagnose AD.